Cal. Health and Safety Code § 4733.5

Where two or more county sanitation districts have joined in the purchase, ownership, use, construction, maintenance, or operation of a sewerage system, or sewage disposal or treatment plant, or refuse transfer or disposal system, or both, either within or without the districts, or have so joined for any combination of these purposes, as provided in Section 4742, and the districts hold their meetings jointly, and one or more of the directors serve as a director on more than one of these districts meeting jointly, the districts may, by joint resolution approved by each district, limit the compensation of a director to compensation equal to not more than fifty dollars ($50) for each jointly held meeting attended by him or her, not to exceed one hundred dollars ($100) in any one month for attendance at jointly held meetings. For purposes of this section, the determination of whether a director’s activities on any specific day are compensable shall be made pursuant to Article 2.3 (commencing with Section 53232) of Chapter 2 of Part 1 of Division 2 of Title 5 of the Government Code.